Hibernate读写Clob和Blob类型字段

最新推荐文章于 2018-06-09 14:48:00 发布

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本文介绍使用 Hibernate 框架进行 Blob 和 Clob 数据类型的处理方法，包括配置 Hibernate.cfg.xml 文件、创建数据库表结构、定义 POJO 类、编写映射文件 TestCB.hbm.xml 及实现 Blob 和 Clob 的存取测试代码。

数据库脚本：

create table testcb(id varchar(32) primary key,name varchar(32),photo blob,description text);

Hibernate.cfg.xml

<?xml version='1.0' encoding='UTF-8'?>

<!DOCTYPE hibernate-configuration PUBLIC

"-//Hibernate/Hibernate Configuration DTD 3.0//EN"

"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>

<session-factory>

jdbc:mysql://localhost:3306/schoolproject?characterEncoding=gb2312&useUnicode=true

</property>

org.hibernate.dialect.MySQLDialect

</property>

<property name="myeclipse.connection.profile">mysql</property>

com.mysql.jdbc.Driver

</property>

org.hibernate.dialect.MySQLDialect

</property>

<property name="current_session_context_class">thread</property>

</session-factory>

</hibernate-configuration>

POJO：

package Search.Clob_Blob;

import java.sql.Blob;

import java.sql.Clob;

public class TestCB {

private String id; //标识id

private String name; //学生姓名

private Blob photo;

private Clob description;

public String getId() {

return id;

}

public void setId(String id) {

this.id = id;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

public Blob getPhoto() {

return photo;

}

public void setPhoto(Blob photo) {

this.photo = photo;

}

public Clob getDescription() {

return description;

}

public void setDescription(Clob description) {

this.description = description;

}

TestCB.hbm.xml

<?xml version="1.0" encoding="utf-8"?>

<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"

"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<!--

Mapping file autogenerated by MyEclipse - Hibernate Tools

-->

<hibernate-mapping package="Search.fetch" >

</id>

</class>

</hibernate-mapping>

准备一个图片sample.jpg放在Clob_Blob包下

写Blob和Clob测试代码：

package Search.Clob_Blob;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileNotFoundException;

import java.io.IOException;

import java.sql.Blob;

import java.sql.Clob;

import org.hibernate.Hibernate;

import org.hibernate.Session;

import org.hibernate.SessionFactory;

import org.hibernate.Transaction;

import org.hibernate.cfg.Configuration;

public class Test {

public static void main(String[] args) {

String filePath=System.getProperty("user.dir")+File.separator+"src/Search/Clob_Blob"+File.separator+"hibernate.cfg.xml";

File file=new File(filePath);

SessionFactory sessionFactory=new Configuration().configure(file).buildSessionFactory();

Session session=sessionFactory.openSession();

Transaction tx=session.beginTransaction();

try {

String imgPath=System.getProperty("user.dir")+File.separator+"src/Search/Clob_Blob"+File.separator+"sample.jpg";

FileInputStream fis=new FileInputStream(imgPath);

Blob photo=Hibernate.createBlob(fis);

Clob description=Hibernate.createClob("this is description");

TestCB testcb=new TestCB();

testcb.setName("tom1");

testcb.setPhoto(photo);

testcb.setDescription(description);

session.save(testcb);

tx.commit();

} catch (FileNotFoundException e) {

e.printStackTrace();

} catch (IOException e) {

e.printStackTrace();

}

、

运行后，在mysql客户端中可以看到已经成功保存：

运行读取测试代码：

package Search.Clob_Blob;

import java.io.BufferedReader;

import java.io.File;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.io.Reader;

import java.sql.Blob;

import java.sql.Clob;

import java.sql.SQLException;

import org.hibernate.Session;

import org.hibernate.SessionFactory;

import org.hibernate.Transaction;

import org.hibernate.cfg.Configuration;

public class TestRead {

public static void main(String[] args) {

String filePath=System.getProperty("user.dir")+File.separator+"src/Search/Clob_Blob"+File.separator+"hibernate.cfg.xml";

File file=new File(filePath);

SessionFactory sessionFactory=new Configuration().configure(file).buildSessionFactory();

Session session=sessionFactory.openSession();

Transaction tx=session.beginTransaction();

//读取clob和blob

String imgPath=System.getProperty("user.dir")+File.separator+"src/Search/Clob_Blob"+File.separator+"sampleread.jpg";

TestCB testcb=(TestCB)session.get(TestCB.class, "1");

Blob photo=testcb.getPhoto();

Clob description=testcb.getDescription();

try {

StringBuffer buffer=new StringBuffer();

Reader reader=(Reader)description.getCharacterStream();

BufferedReader breader=new BufferedReader(reader);

char[] b = new char[60000];//每次获取60K

//将Clob解析成String

int i = 0;

while((i = breader.read(b)) != -1)

{

buffer.append(b,0,i);

}

System.out.println(buffer.toString());

//将Blob还原成文件

FileOutputStream fos=new FileOutputStream(imgPath);

InputStream fis1=(InputStream)photo.getBinaryStream();

byte[] b1 = new byte[60];//每次获取60K

int i1 = 0;

while((i1=fis1.read(b1))!=-1){

fos.write(b1);

}

} catch (SQLException e) {

e.printStackTrace();

} catch (IOException e) {

e.printStackTrace();

}

tx.commit();

}

结果：

Hibernate: select testcb0_.id as id0_0_, testcb0_.name as name0_0_, testcb0_.photo as photo0_0_, testcb0_.description as descript4_0_0_ from testcb testcb0_ where testcb0_.id=?
this is description

红色部分为解析的Clob,同时在Clob_Blob下可以看到生成的sampleread.jpg